Field of the Invention
The invention relates to agricultural tools and more particularly tools comprising mainly one or more wheels.
In tools of this type, the wheel(s) is/are generally used to work the soil. The wheels may operate alone or in conjunction with other portions of the tool.
In the case of a sowing machine, for example, the tool comprises a portion which is provided to open a furrow in the soil, typically a ploughshare, a disc or a tooth, and one or more wheel(s) in order to close the furrow and/or to pack the earth after the seeds have been deposited at the bottom of the furrow.
Some tools, such as the above-mentioned sowing machine, also comprise so-called “depth control” wheels which control the working depth of the remainder of the tool. In the case of a tool comprising a ploughshare, for example, depth control wheels are mounted so as to be fixedly joined to the ploughshare so that, whilst travelling over the ground, the wheels retain the active portion of the ploughshare at a substantially constant depth.
Most often, the wheels with which agricultural tools are provided are intended to travel on the ground. They thus comprise a tire which is mounted around a portion of the wheel which forms the body thereof.
In order to prevent the tire from becoming disconnected from the wheel body during work, the portion of the wheel body which forms the rim is formed in a particular manner. This results in generally complex forms which complicate the production of the wheel body and also the mounting of the tire thereon.
That is the reason for which the wheels often comprise two similar flanges which are mounted one on the other in order to form the body of the wheel. The flanges are assembled one on the other by means of one of the main faces thereof, with the tire being enclosed.
Description of Related Art
In FR 2933903, the Applicant proposed an innovative wheel, whose shape of the wheel body prevents the tire from becoming detached from the rim during operation, including under extreme conditions. The body in question is formed by the mutual assembly of two similar flanges in a state face to face.
When they are used as tools, the wheels are generally subjected to great loads during operation.
In some cases, in particular when a sowing machine is provided therewith, the orientation of the wheel in the machine does not correspond to the advance direction of the machine: it is often the case that the wheel is inclined to a great extent in relation to the advance direction. Furthermore, the wheel may be inclined in relation to the vertical relative to the ground. During operation, this results in very great stress on the wheel body.
Some of those wheels comprise a rim and a hub which are connected by arms. The arms ensure the mechanical connection and the transmissions of forces necessary for the operation of the wheel whilst leaving passages free between the arms. The wheel is thus an open-disc type wheel.
Open-disc type wheels require few raw materials and are light. The free passages make one side of the wheel accessible from the opposite side. For example, an operator can reach down to the bottom of a wheel passage of an agricultural machine without disassembling the wheel from its axle. The free passages are generally sufficient for an operator to introduce his hands, his arms and tools therein. An operation for cleaning the machine and the wheels is rapid and efficient, for example, by means of a pressurized water device. This may be particularly appreciated for cleaning and maintaining machines which are used on sticky and muddy soils, such as sowing machines: the accumulations of earth which tend to harden and damage the machine may be readily removed.
Agricultural machines provided to travel over ground covered with straw and dry residues generally have solid-disc type wheels. The rim and the hub are thus connected to each other by a solid disc.
Solid-disc type wheels prevent the appearance of air flows through the wheels. Solid discs prevent the production or amplification of occurrences of turbulence of air around the machine during movement. If open-disc type wheels were used, the arms would behave in an illustrative manner like the blades of a fan. Consequently, the dry residues would be carried along and clouds of dust would be produced. Such clouds of dust impair the driver of the machine, reducing his visibility, making the air difficult to breathe and rapidly making the machine dirty. This also leads to pollution of the adjacent plots of land.
Open-disc type wheels of agricultural machines provided for working moist soil are poorly adapted to travel over ground which is covered with straw and dry residues.
An objective of the Applicant is to improve the situation.